There are small air ionizers that plug into the dash that claim to destroy smoke odor. There are also replacement ashtrays with built in ionizers that claim the same thing "negative ion showers", etc. These devices may cut down the odor some, but also produce ozone (bad for your lungs and the car plastic and rubber parts) and tend to plate out the ionized particles as a soot colored dust in the home units, so I imagine they would do the same thing in a car.
Probably what would work the best is a charcoal/hepa air filter unit in the car. Your 'air fresheners' don't destroy or capture the smoke, just mask it with a different odor. Smoke has both gaseous and particulate components. The activated charcoal and zeolite will help capture the gaseous mode, and the HEPA filter traps the particulates, usually expressed as a capture efficiency for a minimum particle size. You would ideally like an air cleaner/filter that says something like "captures 99.5% of particles down to 0.5 microns" (Better would be '99.9% down to 0.1 microns'). The volume processed by the cleaner is another factor - the greater the volume in cubic feet per minute, the faster the air is being filtered.
If you are really compulsive about this then probably the best filtering you could accomplish is to remove both rear speakers and have one speaker hole ducted to an AustinAir Junior air cleaner (
http://www.austinair.com/specs.htm ), and the other speaker hole accepting the clean air output of the cleaner. Run the whole thing off a power inverter - about 80 watts maximum draw.
Good luck. If you find an inexpensive highly effective answer, let me know, and we will get rich selling it to coal burning electric generating stations! EACH 1000 megawatt coal burning power plant (and the US has lots - they provide 51% of US electricity) pumps out 6,500,000 tons of gaseous waste per year, and 320,000 tons/year of particulates as fly ash, which includes 400 tons of heavy metals, 3 tons of uranium, and 8 tons of thorium! Now THAT is a smoke problem!!!
[Edited by JCE on 04-26-2001 at 11:48 PM]